## ajprincess Group Title Plzzz help. the following figure shows a long wire carrying a current of 30A. The rectangular loop carries a current of 20A. Calculate the resultant force acting on the loop. Assume that a=1cm, b=8cm and l=30cm. 2 years ago 2 years ago

1. ajprincess Group Title

|dw:1337319857835:dw|

2. timo86m Group Title

What is B?

3. ajprincess Group Title

u mean my answer for B?

4. timo86m Group Title

I think it will involve integration.

5. ajprincess Group Title

|dw:1337320632924:dw| This is to find the force on the second current conductor.

6. ajprincess Group Title

Sorry so bad at drawing. :(

7. timo86m Group Title

ah ok i think i found it in book i wil lattach 2 files hold on

8. timo86m Group Title

9. timo86m Group Title

10. timo86m Group Title

hope it helps

11. ajprincess Group Title

Ya. it helps a lot. Bt y hav they given the value of l. It is askd to find the resultant force.

12. timo86m Group Title

i is amps. Is that what you mean?

13. ajprincess Group Title

No. In ur attachment the question is to fin the magnetic force on the top of the wire b. And in the equation given in the solution there is no l bt only a nd b r there. in my question the value of l is also given. I am wondering y that was given and the magnetic force askd to b found here is the resultant.

14. ajprincess Group Title

i mean top of the wire of length b.

15. timo86m Group Title

Not sure just solve for whatever variable or convert. :) but the diagram is almost exactly the same :)

16. ajprincess Group Title

ha k. thannnnxxxxxxxx a lot.

17. timo86m Group Title

:)

18. ujjwal Group Title

19. ajprincess Group Title

i get a different answer. Bt can u pls show me hw u got ur answer if u dnt mind?

20. ajprincess Group Title

@ujjwal

21. ujjwal Group Title

sure, the |dw:1337350437168:dw| there exists an attractive force F1 and a repulsive force F2 between the wires carrying 30 amp and 20 amp.. Calculate both forces and find their difference.. that's all..

22. ajprincess Group Title

which formula did u use here to find it?

23. ajprincess Group Title

did u round it off?

24. ajprincess Group Title

@ujjwal

25. ajprincess Group Title

i got the answer as 0.00315N.

26. ujjwal Group Title

It involves large numbers.. your answer seems to be correct.. I used the relation$F=mu _{0}I _{1} I _{2}l/2pi r$

27. ujjwal Group Title

what's wrong with OS? but i guess you got the relation i used...

28. ajprincess Group Title

ya. do u knw how to derive this relation from this |dw:1337397048799:dw|

29. ajprincess Group Title

|dw:1337397220582:dw|

30. ujjwal Group Title

I guess i can't see the whole relation.. I can't see it at rightmost part.. Is there a lower limit?? It's a line integral in closed path , isn't it? why do you need limits?? I can't see the whole relation though..

31. ajprincess Group Title

|dw:1337397679038:dw|

32. ajprincess Group Title

|dw:1337397784654:dw| This formula is to find the force on the second conductor. Can u @Shivam_bhalla explain hw it becomes |dw:1337397890531:dw|. Plzzzz.

33. shivam_bhalla Group Title

@ajprincess , Take a look here -->http://cnx.org/content/m31103/latest/

34. shivam_bhalla Group Title

The above link for magnetic field due to a wire and its derivation. Now I will explain that concept which you want me to do so.

35. shivam_bhalla Group Title

|dw:1337353084406:dw| Consider 2 parallel wires carrying current I_1 and I_2 Force exerted by wire 1 on wire 2 is F= (B_1) (I_2)(distance between two wires)

36. shivam_bhalla Group Title

Sorry I wrote that in a hurry. It should be F= (B_1) (I_2)(length of wire 2) Now as in the previous link I gave to you, we see that $B_1 = \frac { \mu_0 I_1 }{2 \pi r}$ $F=B_1I_2(length \space of \space wire \space 2)$ $\frac{F}{length \space of \space wire \space 2} = \frac { \mu_0 I_1 }{2 \pi r} I_2$ $f=\frac { \mu_0 I_1I_2}{2 \pi r}$ where$f = \frac{F}{length \space of \space wire \space 2}$

37. ajprincess Group Title

Thanxxxx a lot @Shivam_bhalla

38. ajprincess Group Title

Thanxx a lot @ujjwal

39. shivam_bhalla Group Title

yw :)